High-speed compressed-air circuit breaker



y 7, .53 B. P. BAKER 2,644,876

meas ssn COMPRESSED AIR. cmcuxpaawsa Filed Aug. 19. 1950 WITNESSES:INVENTOR Benjamin P. Baker.

ATTORNEY Patented July 7, 1953 HIGH-SPEED COMPRESSED-AIR CIRCUIT BREAKERQ Benjamin F. Baker, Turtle Creek, Pa., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., a corporation ofPennsylvania Application August 19, 1950, Serial No. 180,447

20 Claims.

My invention relates to high-speed compressed-air circuit-breakerassemblies of either the single-action type or of the multiple-action orrecloser type. My invention also relates to features which are useful inrecloser types of compressed-air breakers, whether the operation is atextremely high speeds or not.

The general concept and specific embodiment of my present invention isan improvement over the breaker-assembly which is the subject of acopending application of Howard M. Wilcox and myself, Serial No. 73,516,filed January 29, 1949, in which the air-blast interrupter-assembly wasmounted on the top of an insulating blast-tube which extended up from acompressed-air tank which was located at groundpotential. In such adevice, a large volume of high-pressure air was trapped in the longinsulating blast-tube, which had to have a substantial length,sutficient to provide the necessary insulating-distance for withstandinga substantial elevated line-potential. This large volume ofhigh-pressure air, filling the long insulating blast-tube of said priordevice, delayed both the opening action and the reclosing action of theblast-responsive contacts, because of the time necessary to bring theblast-tube air up to pressure in the first place, and to exhaust it inthe second place.

The type of air-blast breaker to which my present invention is moreparticularly directed uses a substantially closed exhaust-chamber whichhas a volume designed so that it will reach about half of theair-pressure of the applied air-blast in about the time necessary forthe arcinterrupting contacts to open far enough to extinguish the arc,as described and claimed in a copending application of Frisch, Aspey,Mac- Neill and myself, Serial No. 74,406, filed February 3, 1949, now U.S. Patent 2,627,005, issued January 27, 1953. This is usually quite adesirable feature of construction, particularly in air-blast breakers ofany substantial high-voltage or highcurrent rating, as it maintains apressurized area at the arc-interrupting gap, thus mate riallyincreasing the breakdown-voltage of the gap, and enabling a small,short-stroke gapdevice to handle millions of kilovolt-amperes, thus notonly reducing the size and, therefore, the cost of the breaker, but alsoreducin the time of operation, because of the shortened stroke.

It is an object of my present invention to retain the advantages and toovercome the aboveindicated disadvantages of both of t ese P vious typesof air-blast breakers. The disadvantage of a long insulating blast-tubeis avoided, in my invention, by mounting the compressed-air tank on thetop of the necessary insulating support, so that the tank is at the sameelectrical potential as'the arc-interrupting parts, and thus theblast-tube may be made of metal and may be extremely short.

I retain the advantage of a substantially enclosed exhaust-chamber,while still permitting fast reclosure, by adding suitable means, as willbe described, for dumping the air out of the exhaust-chamber as soon asthe fault-current is interruptedby the operation of the arcing contacts,this dumping operation being performed without waiting for an operationof the serialll connected isolating switch which is used with suchair-blast breakers. Then, if the fault still persists, theblast-operation will be repeated, and the dump-valve on theexhaust-chamber will be reclosed.

In accordance with my present invention, I also retain, withmodifications, the essential advantages of a known operating-mechanismfor the isolating-switch. As shown and described in the aforesaidcopending application of Wilcox and myself, Serial No. 73,516, filedJanuary 29, 194.9,this known isolating-switch mechanism was triggeredoil by an air-pressure derived from the lower end of the long insulatingblast-tube of the previous construction. In my present invention, Iderive this initiating air-pressure from my short blast-tube which is ata considerable height above the ground-level of the operating-mechanism,and I use an insulating duct which, by reason of its length, introducesa desirable time-delay element. The lastnamed copending application alsoshows an interlocking means, responsive to the opening of the isolatingswitch, for reclosing the blastvalve. I retain this feature, withmodifications adapting it to recloser-breakers.

With the foregonig and other objects in view, my invention consists inthe combinations, as-

- semblies, systems, structures, parts and methods of design andoperation, hereinafter described and claimed, and illustrated in theaccompanying drawing, the single figure of which is a side elevationalview, partly in section, and largely diagrammatic, not to scale,indicating the general principles of my invention.

The drawing shows a single pole of a compressed-air breaker-assemblyembodying my invention. It is to be understood, however, that myinvention is often or usually applied to a threephase power-system (notshown), in which case each pole would consist of the structure as shown,except that a single operating-mechanism may be used for thegang-operation of the isolatingswitches of all three poles.

My illustrated compressed-air circuit-breaker assembly comprises anair-blast interrupterassembly I, mounted on the top of an insulatingsupporting-means 2, which stands high enough to provide a sufficientinsulating-distance from a substantial elevated line-potential toground.

In the drawing, I have illustrated a singlecolumn interrupter-assemblyI, comprising two vertically aligned, self-opening, longitudinalblastmain interrupter-gap devices 3 and 4. In accordance with my presentinvention, the bottom gap-device 3 is mounted directly on top of acompressed-air tank 5, in which air is maintained under a suitablepressure, such as 250 pounds per square inch, by any suitablecompressed-air supply-means, represented by a downwardly extendinginsulating air-supply tube 6. The gap-devices 3 and 4 are electricallyconnected in series, so that the current-flow, in the normal closedposition of the breaker, is from the line Li to the top 1 of theinterrupterassembly I, thence through the two gap-devices 4 and 3 to thebottom I of the interrupterassembly I.

Each interrupter-gap device 3 or 4 comprises a stationary contact-member3S or 48, a the case may be, and a vertically movable contact member 3Mor 4M, respectively. The two movable contact-members 3M and AM arenormally biased towards their closed poistions by means of biasingsprings 33 and 4B, respectively.

In the construction which is very much preferred, the stationarycontact-member 38 of the lower gap-device 3 is integrally orelectrically united, at its lower end, with a substantially closed lowerexhaust-chamber 3E, which i made of metal. The lower stationarycontact-member BS is hollow, and extends down into the lowerexhaust-chamber 3E, as shown at 3. The top end of the lower stationarycontact-member 38 is provided with an orifice 3-0 which is normallyclosed by the abutment of the movable contactmember 3M thereagainst, inthe normal closed position of the breaker.

The two movable contact-members 3M and AM are mounted within a metallicmoving-contact assembly or housing I, which is in the form of twoconcentric cylinders, namely an inner cylinder 1i and an outer cylinderTo, so as to provide an annular space is between these cylinders,through which the air-blast may pass. The moving-contact housing I isdisposed between the two stationary-contact assemblies 3S and 4S, beingheld in place by means of two insulating tubes 3-I and 4-1 respectively.The lower insulating tube 3-]: abuts against the lower exhaustchamber 3Eand supports the outer cylinder 10 of the moving-contact housing I. Thislower insulating tube 3-1 is larger than the lower stationarycontact-member 3S, so as to provide an annular space 35 therearound,through which the air-blast may pass, as will be subsequently described.

It is an important feature of my present invention that I provide theshortest possible blasttube 8 for, at times, supplying a blast of airfrom the compressed-air tank 5 to the bottom of the annular space 33 ofthe bottom gap-device 3. This blast-tube 8 is shown as comprising afunnellike air-guiding duct which is integral with the lowerexhaust-chamber 3E, and which extends vertically all the way throughsaid exhaustchamber The small lower end of the funnellike blast-tube 3is in hermetically tight communication with the compressed-air tank 5,and this communication is normally closed by means of a blast-valve 9,which is located inside of the compressed-air tank 5, and which isnormally pressed up against the open bottom end of the blast-tube 8, byany suitable means, preferably in the form of a valve-operating meanswhich is accessible and operable from the bottom of said compressed-airtank 5.

The blast-valve 9 is in the form of an inverted cup, which is providedwith a pressure-chamber l0 back of it, that is, underneath it, so thatthe blast-valve 9 is closed whenever compressed air is supplied. to itspressure-chamber l0, through a downwardly extending pipe I0. When thecompressed air in thispressure-chamber I0 is dumped or evacuated, theair-pressure within the compressed-air tank 5 forces the blast-valve 9open, so as to supply a strong blast of air to the interrupter-assemblyI. The blast-valve 9 is illustrated as being provided with a lightclosingspring I l.

The bottom end 3' of the lower stationary contact-member 38 is supportedin spaced relation within the funnel-like blast-tube 8, so as to providean annular space 8s around said lower end 3 within said blast-tube. Thissupportingmeans for the lower end 3 of the bottom stationarycontact-member 38 is shown in the form of a plurality of horizontalhollow or tubular bosses I? which serve jointly as the supportingmeansfor the lOWer stationary contact-member 3S, and as the means forestablishing a communication between the lower end of this contactmember38 and the lower exhaust-chamber 3E.

The upper stationary contact-member HS is integrally or electricallyunited with an upper exhaust-chamber 413, which is similar to the lowerexhaust-chamber 3E, except that it lacks the blast-tube 8. The upperstationary contactmember 4S is also of hollow construction. The lowerend of this upper stationary contact-member 43 is provided with anorifice 4-0, which is normally closed by the upper movable contactmember4M. The upper end of the hollow upper contact-member ts is incommunication with the substantially closed space within the upperexhaust-chamber 4E. This upper exhaust-chamber 4131 is supported on thetop of the upper insulating tube 4-1, the bottom end of which rests onthe top of the outer cylinder To of the moving-contact housing 1. Thisupper insulating tube 4-I is also larger than the upper stationarycontact-member 48, so as to provide an annular space 45, which forms aclosed upper end for the blast-air, as this blast initially movesupwardly through th interrupter-assembly I.

As a result of the construction thus far described, when the blast-valve9 is opened, a blast of air moves rapidly upwardly through the shortblast-tube 3, the lower insulating tube 3-1, the outer cylinder 10, andthe upper insulating tube 4-1, quickly creating an air-pressure which.forces open the two movable contact-members 3M and 4M against thepressure of their closing-springs 3B and 4B. In a sense, the entiretubular structure, including the elements 8, 3-1, lo and 4-1, may beregarded as comprising the blast-tube of the device. As long as asubstantial air-pressure is maintained in this blast-tube, in the spacessurrounding the lower and upper gaps 3 and 4,

these gaps will be opened by the action of the air in pressing back themovable contact-members 3M and 4M, drawing an are at each gap. Thecompressed air of the blast will rush into the uncovered orifices 3-0and 4-0 at the front or entrance-ends of the respective hollowstationary contact-members 3S and 4S, and will exhaust into therespective exhaust-chambers 3E and 4E.

As set forth in the application Serial No. 74,406, the size orvolumetric capacity of each of the exhaust-chambers 3E and 5E is suchthat the pressure in, each chamber will build up to about half of thepressure of the blast-air surroundin the respective gaps, in about thetime necessary to insure arc-extinction between the contact-gaps 3 and4. This air-pressure, which is built up in the two exhaust-chambers 3Eand 4E, is quite useful in pressurizing the gap-devices 3 and 4 at themoment of, and immediately after, the interruption of the arc, so as toincrease the breakdown-voltage of the gaps, thus making is possible touse a shorter gap-separation, with a consequently faster operationbecause of the shortened gap-interrupting distance, and with smaller andless expensive parts.

As with all air-blast interrupters of this type. it is obvious that themovable contact-members 3M and 4M will remain open, only as long as anadequate air-pressure is provided in the regions immediately surroundingthe gaps, as otherwise the closing-springs 3B and 4B will close thesegapdevices. It is also obvious that it would not generally be feasibleto maintain the fast-moving air-blast any longer than is absolutelynecessary to safely interrupt the line-current and to guard against therestriking of the arc.

In common with other air-blast gap-devices of this general nature,therefore, I provide an isolating-switch Ht'which is electricallconnected in series-circuit relation to the main interrupter-gapassembly I. In the illustrated form of embodi ment of my invention, oneend of the isolatingswitch 16 is pivoted at I! to the bottom portion I"of the interrupter-assembly I. The free end of the isolating-switch I6is movable into and out of contact with suitable contact-fingers [8which are carried by a metal cap-piece I9 on top of an insulatingsupporting-column 2G. The metal cappiece 19 constitutes a line-terminalof my breakerassembly, being connected to the second lineconnection L2.

As shown and described in the application Serial No. 73,516, myisolating-switch I6 is operated by a pneumatic operating-mechanism ordrive-mechanism 23, which is disposed at substantially ground-potential,being usually located on or near the ground. The operating mechanism 23is provided with an operating-piston 24 which reciprocates a rack 25,which rotates a pinion 2% through a limited motion of approximately 180.The pinion-shaft 2'! has a drive-connection 28 to a crankshaft 29 havingcrank-members 3| which are connected to the isolating-switch l6 throughan insulating switch-operating rod or linkage 32. The linkage-connection32 is made in such manner that, at each of the extreme limits of themotion of the crankshaft 29, the insulated switchoperating rod 32 is incomplete toggle, so that the isolating-switch I8 is locked in both itsopen position and its closed position, thus avoiding rebound.

The pinion-shaft 21 of the operating-mechanism 23 is illustrated asbeing provided with two auxiliary attachments. One of these attachmentsis a compression-spring linkage 40, which is crank-connected to thepinion-shaft 21, as indicated at in such manner that thecompression-spring of this linkage 40 presses the pinion shaft 2'!toward either one of its limits of travel, once it has passed itscentral or 90 point in its travel from one extreme limit of motion tothe other extreme limit of motion. This compression-spring linkage thusserves to hold the pinion shaft 21 in its extreme limit of motion, ateither end of its direction of movement, so as to hold the crankshaft 29in such position that the previously mentioned toggle-lock is provided,for holding the isolating-switch l6 against rebound.

The second auxiliary attachment which is associated with thepinion-shaft 2! of the operating-mechanism 23 is a shock-absorber, whichis diagrammatically indicated at M, and which is crank-connected to thepinion-shaft 21, as indicated at 4|, in such manner as to stronglyretard the last half of the rotating-movement of the pinion-shaft 21,during either direction of movement of said pinion-shaft. During thefirst half of the movement of the pinion-shaft 21, from either extremelimit of its motion, the

shock-absorber 4! is extended or lengthened, and

it offers practically no opposition to such lengthening movement. Afterthe pinion-shaft 21 passes its midpoint or 90 point, it begins tocontract the shock-absorber 4!, or to push together its telescopingcylinders. This contraction is very slow and gradual at first, but itbecomes extremly rapid as the pinion-shaft 21 approaches the extremelimit or end of its motion. The shock absorber 4i opposes thiscontraction, with a force which increases very rapidly as the velocityof compression is increased.

The general-effect of this shock-absorber 4| is to slow down the speedof rotation of the pinionshaft 2?, particularly as it approaches the endof its motion, and as a result of this slow-down action, thepinion-shaft has a more nearly uniform speed of rotation or movement, asdis tinguished from-being constantly accelerated under the influence ofthe operating-force which is applied to it from the operating-mechanism23, aswill be subsequently described. In fact, the reaction of theshock-absorber actually decreases the angular velocity of thepinion-shaft, at or near the end of its travel.

The operating-mechanism 23 includes also a double-piston air-valve 45,disposed with its two pistons 450 and 450 opposing each other. Theleft-hand air-valve piston 450, which controls the opening or" theisolating-switch I6, is preferably larger than the right-hand piston450', which controls the closing of the isolating-switch [6. Each of theair-valve pistons 450 and 450 is provided with its own air-inletpipe-means 460 and 460, respectively, for applying air, under pressure,to the respective air-valve pistons.

The air-valve is provided with ports 41, 48, 59 and 563,- which are soarranged that, when the switch-opening piston 450 is subjected toairpressure from its inlet-means 460, it moves to the right, thusclosing the dump-port 4'! which dumps the air from the left-hand side ofthe operatingpiston 2 and at the same time it opens the inletport 48which leads the inlet-air into this left hand side of theoperating-piston 24 thus driving said operating-piston to the right, ina switchopening movement. At the same time, the abovedescribed movementof the left-hand air-valve piston o pushes the right-hand piston 450over to the right, thus causing it to open its dumppoi't A9 and to closeits inlet-port 5 0 which, when open, connects the space to the right ofthe operating-piston 24 with the closing-piston airinlet pipe-means 460.

It will be understood that the first-mentioned inlet and dumping ports48 and 41 are both connected to the space to the left of theoperatingpiston 24, while the other inlet and dumping ports 50 and 49are both connected to the space to the right of the operating-piston 24,the two dumping-ports 4! and 59 being for the purpose of exhausting airto the atmosphere, while the respective inlet-ports 48 and 50 are forthe purpose of supplying air-pressure to the operating-piston 24 fromone or the other of the air-inlet pipes 460 and 460, as the case may be.By this means, I provide what is known as functional dumping, fordumping the air which would otherwise be trapped behind theoperating-piston 24 when said piston is being moved in either directionof its travel.

In accordance with my present invention, I use the switch-openingair-valve piston 450 as a pressure-responsive control-mechanism,disposed at substantiallyground-potential, for controlling theinitiation of the actuation of the drive-mechanism 23 in theswitch-opening direction. To this end, I connect the switch-openingair-inlet pipe 460 to a vertical insulating pipe or aircommunicatingmeans i, which extends up to the interrupter-assembly I, and which is incommunication, through a pipe 52, with the inside of the blast-tube 8.The length of the insulating pipe 5| is at least approximately as longas the insulating-distance or height of the insulating supporting-means2 for the interrupterassem- 1013 l, and this pipe-length is suflicientto provide a substantial time-delay between the blast-off of theair-blast interrupter-assembly and the application of an air-pressurefrom the blast-tube B to the control-mechanism 450 which causes anopening-movement of the isolating-switch H5.

In accordance with my invention, I provide a ,ine-fault-responsivemeans, of any suitable kind, for responding to fault-conditions whichnecessitate an opening of my breaker-assembly. Such a fault-responsivemeans is typified by an overcurrent relay 53, the operating-coil ofwhich is energized from the line L2. The overcurrent relay 53 has arelay-contact 54 which is used to energize a trip-circuit 55 whichenergizes an electro pneumatic tripping-valve 56 which is used tocontrol a reciprocating air-pressure motor 51. The motor 51 has a piston58, and a pistonchamber 59 above said piston 58. An upwardly extendinginsulating piston-rod 60 serves to control the operation of theblast-valve 9, as will be subsequently described.

The electro-pneumatic tripping-valve 56 is connected, to thepiston-chamber 59 through a pipe 62. In the normal deenergized positionof this tripping-valve 56, as shown, the pistonchamber pipe 62 isexhausted to atmosphere. through the vent-port 63 of the valve. When thetripping-valve 56 is electrically energized, the pneumatic connection tothe vent-port 63 is closed, and the piston-chamber pipe 62 is connected,instead, to an air-pressure pipe 64 which is connected to thecompressed-air supply 6.

The top of the insulating piston-rod 60 of the air-pressure motor 51 isconnected, through a walking-beam or lever 65, to a pilot dump-valve 66.In its normal non-actuated position, the pilot dump-valve 56 connectsthe pressure-chamber H] of the b1ast-valve 9 to the air-pressure; withinthe compressed-air tank 5, so as to keep the blast-valve 9 closed. Whenthe piston-rod 60 is lowered, in response to the electrical energizationof the electro-pneumatic tripping-valve 56, the walking-beam 65 movesthe pilot dump-valve 66 upwardly, against the action of itsbiasingspring 61. When the pilot dump-valve 66 moves up, into itsoperated position, it closes off the connection between thepressure-chamber l0 and the compressed-air tank 5, and opens a vent-port6B, which dumps the air from the pressure-chamber l0 and thus permitsthe pressure of the air in the compressed-air tank 5 to push open theblastvalve 9.

With a fault-responsive controlling-means as thus-far described, it willbe evident that the blast-valve 9 will be opened Whenever there is afault of predetermined magnitude on the line LlL-2; and it will befurther evident that the blast-valve 9 will remain open as long as, andonly as long as, the fault-responsive overcurrentrelay 53 continues tobe actuated. As soon as the fault-current is interrupted, as by theinterruption of the arcs drawn by the main gap-members 3 and 4 of theinterrupter-assembly, the overcurrent relay 53 and hence theelectro-pneumatic tripping-valve 56 will be instantly deenergized.Hence, pressure will be removed from the piston-chamber 59 of theair-pressure motor 51, and the piston-rod 60 will move up again, inresponse to the pressure of the biasing-spring 81 of the pilotdump-valve 66. In the same moment, the pilot dump-valve 66 will returnto its normal non-actuated position, in which it supplies pressuredirectly from the compressed-air tank 5 to the pressure-chamber I0 ofthe blast- Valve 9, instantly closing the latter.

It is a desirable feature of my invention, that means shall be providedfor obtaining a repeater-operation of my air-blast interrupterassembly1, without waiting for the more sluggishly acting isolating-switch IE toopen its con tact at the contact-fingers [8. It is also necessary, orexceedingly desirable, to build up pressure in the substantially closedexhaust-chambers 3E and 4E during the blasting-off of theinterrupter-assembly, as previously described. If there is to be arepeater-action, some suitable means has to be provided for rapidlydumping the pressurized air in the exhaust-chambers 3E and 4E, wheneverthe blast valve 9 is reclcsed. Then, if a line-fault still persists,which has not cleared itself during the brief time during which the linehas been deenergized by the action of the breaker, the overcurrent relay53 will again instantly be actuated, as soon as the main gapdevices 3and 4 close, thus instantly initiating a second blast-off operation.

In order to quickly dump the air from the exhaust-chambers 3E and 4Ewhenever the blast-valve 9 is reclosed, I provide each of theseexhaust-chambers with a dump-valve 3D or 4D, as the case may be. Each ofthe dump-valves 3D and 4D is provided with a piston 15] which isprovided with a piston-chamber Ti above it, and also alight-compression-spring 12 in this piston-chamber. When there is noexternally applied air-pressure in the piston-chamber H, butair-pressure in the exhaust-chamber 3E or 4E as the case may be, theair-pressure of the exhaulst-chamber raises the piston 10 and. opens avent-port 13, which quickly exhausts the air in the exhaust-chamber 3Eor 4E as the case may be. When this exhaust-chamber air is reducednearly to atmospheric pressure, the compression- 9 2. spring 12 pushesdown the piston 10. and closes the vent-port l3. e

valves 3D and 4D are connectedto, an air-pipe 14, which is connectedtoa. pilot dump-valve 15.

The pilot dump-valve 15 is. operable-gin its non-i actuated position, asshown, to vent the pipe "I4 through vent-ports 16, so as to vent thepistonchambers H of the two dump-valves 3D and 4D. Under theseconditions, there is no externally applied air-pressure on thedump-valves 3D or 4D, and these valves are free .to open in response toany substantial air-pressures which may exist Within their respectiveexhaust-chambers 3E or 4B. The pilot dump-valve 1'5 is held, in itsillustrated non-actuated position, which is its uppermost position,by'meansofthe walking-beam lever 65 and the top end of the piston-rod 60of the air-pressure motorfi'l.

When a fault occurs; the air-pressure motor 51 moves itg-p-istoh-rod 5i:downwardly, thus permitting the pilot dump-valve '55 to operate, underthe bias of its compression-spring ll, thus closing the vent port 15-3and connecting the dump-valve pipe 74 to-the pipe 52 whichis incommunication with the inside of the blast-tube 8. As soon, therefore,as' the blast-off action begins, and pressure 'builds up intheblast-tube 8, external pressure is applied, through the pipe 52 andthe (now-actuated) pilotdumpwalve 5, to the pipe I4 of the dump-valves3D and 4D, thus holding these dump-valves firmly down in theirclosed-cit positionsso that, when air-pressure builds up intheexhaust-chambers 3E and 4E, said exhaust-chamber pressure will not beable to open the dump-valves 3D and AD, as long as the pilotdump-valve15 remains in its lowermostor operated position.

In any repeater-breaker assembly, some sort of counting-mechanism mustbe provided, for limiting the permissible number of times the breakercan keep on rapidly opening and closing automatically, in case of apermanent linefault which Will not clear itself.- To this end, I haveshown, associated with the overcurrent relay 53, a self-resettableoperation-counter 8?], which counts a predetermined number of rapidlyrecurrent breaker-operations, and then closes a make-contact 8| whichenergizes the trip-circuit 55 independently or" the continuance of afaultcondition. When this happens, the'blast-valve 9 isheld open,instead of reclosing as soon as the arcs have been interrupted atthe'main gapdevices 3 and 4. The operation-counter 8B is i1- lustratedas having a second make-contact 32 which energizes a normally closedelectrically operated switch-opening valve 83 in the switchopeninginlet-pipe 460, so as to open this valve after a predetermined numberottreclosures; Pressure from the blast-tube 8 builds up at the bottomend of the insulating pipe 5i, andwhen the electrically operatedswitch-opening valve83 opens, it transmits the air-blastpressure fromthe blast-tube B to the switch-opening valve 450 of theoperating-mechanism 23, thus initiating the operation of thisoperating-mechanism, and opening the isolating-switch l6. 1

In accordance with. the mode of operation which is provided for in thepreviously-mene tioned application Serial No. 73,516, the end of theoperating-mechanism. rack 25 is provided with a switch-contact 84, whichopens near the end of the opening-movement ofthe isolatingswitch It, andthus breaks the trip-circuit 55, thus deenergizing the electro-pneumatictrip- 10 ping-valve 55, causing the blast-valve 9 to be closed, andcausing the dump-valves 3D and 4D to be opened.

Once the, operating-mechanism 23 has been actuated in a switch-openingdirection, the isolating-switch I6 is locked open by toggle-action,so-that there is no danger of its rebounding closed again.

In order to provide means for reclosing the isolating-switch It, inorderto restore service to the line Li-LZ, I have provided anelectrically energized switch-closing valve 85, which is illustrated ashaving an operating-coil which, when electrically energized, opens theclosingvalve, and-admits compressed air from the pipe 64 to theswitch-closing air-inlet pipe 460 of the air-valve d5 of theoperating-mechanism 23.

The operation of my device has been explained as the description hasproceeded, so that no further explanation should now be necessary.

, I wish it to be understood that I am not at all limited to the precisedetails which have been shown. The drawing has been very much idealizedor simplified, in an effort to clarify the essential operation of thenovel features which I have introduced in accordance with my ments, andas embracing all means. for performing the elemental functions oroperations which I have combined for the first time in a usefulcircuit-interrupter assembly, as herein described. In other words, Idesire to claim broadly all equivalent forms or Variants of the variousmeans for performing or achieving the distinctive individual orelemental operations or steps leading tothe ultimate, composite result;so as to cover all machines having the distinctive essential law ofaction which I have described. There are also many details andsafeguards, which will be apparent to those familiar with the art, manyof which would be used in the actual practice of my invention.

While I have illustrated only one compressedair tank 5, which is used tosupply an air-blast to two main gap-devices 3 and 4, I wish it to beunderstood that a separate compressed-air tank could be provided foreach of the main gap-devices, each tank with its own blast-valve andblast-tube.

With the special dump-valves 3D and 41) which I have provided for theexhaust-chambers 3E and 4E, it is usually not necessary to provide willgradually exhaust the exhaust-chamber, in

readiness for another breaker-operation whenever another fault occurs.Usually this ventingoperation will be completed before the breakerpotential and having 11 is restored to service, in the case ofsingle-operation breakers.

I wish it to be understood, also, that my invention is not limited tothe simultaneous use of all of the novel features which I havedisclosed, as any one or more of the novel features may be employed,singly, or in various combinations with each other, within the intendedscope of my invention. I desire, therefore, that the appended claimsshall be accorded the broadest construction consistent with theirlanguage.

I claim as my invention:

1. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufficient insulatingdistance from asubstantiall ground-potential surface to withstand. a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, a compressed-air tank alsosupported by said insulating supporting means at an elevated potential,a short blast-tube for at times supplying said interrupter-gap devicewith an air-blast from said tank, and a normally closed blast-valve forcontrolling the communication between said blast-tube and the tank, anisolating-switch; means for electrically connecting the isolating-switchin series-circuit relation to the main interrupter-gap device; adrivemechanism disposed at substantially groundinsulating drive-meansconnected to said isolating-switch for opening and closing the same; apressure-responsive controt-mechanism disposed at substantiallygroundpotential for controlling the initiation of the actuation of saiddrive-mechanism in the switchopening direction; and communicating-pipemeans for connecting said control-mechanism in responsive relation tothe air-pressure within said blast-tube, said communicating-pipe meansincluding an insulating pipe-length at least approximately as long asthe insulating-distance of the insulating supporting-means forinterrupterassembly, said pipe-length being suiiicient to pro-- vide asubstantial time-delay between the blastofi of the air-blastinterrupter-assembly and the application of an air-pressure responsivethereto to said control-mechanism.

2. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a suflicient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mountedcompressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallclosed blast-valve for controlling the communication between saidblast-tube and the tank, said main interrupter-gap device including ahollow elongated stationary contact-member having an orifice in itsfront end, a substantially closed exhaust-chamber at the rear end ofsaid stationary contact-member in air-communication with its hollowinterior, and a moving-contact assembly comprising a spring-closed,longitudinally movable contact-member normally abutting against thefront end of said stationary contactmember and in such positionsubstantially covering said orifice; in combination with: apressureresponsive dump-valve for at times quickly dumping thecompressed air out of said exhaust-chamber, said dump-valve beingopenable in response to air-pressure within said exhaust-chamber, andbeing closable in response to an externally applied airpressure; a pilotdump-valve operable, in its nonactuated position, to vent saiddump-valve so that it has no externally applied air-pressure, said pilotdump-valve being operable, in its actuated position, to furnish saiddump-valve with externally applied air-pressure from the blast-tube ofthe interrupter-gap device; and means for actuating both the blastvalveand the pilot dump-valve.

3. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufficient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallyclosed blast-valve for controlling the communication between saidblast-tube and the tank, an electrically controlled fault-responsivemeans for causing the operation of the blast-valve during line-faultconditions on the circuit-breaker and for interrupting the operation ofthe blastvalve during fault-free conditions; a counting mechanism forcounting rapidly recurrent linefault responses and for operating, at theend of a predetermined count, to cause the operation of the blast-valveto continue independently of fault-conditions; an isolating-switch;means for electrically connecting the isolating-switch in series-circuitrelation to the interrupter-assembly; a drive-mechanism for opening andclosing the isolating switch; a pressure responsive switch-controllingmeans for automatically controlling the actuation of saiddrive-mechanism in the switch-opening direction; a normally closedswitch-opening control-valve in said pressure-responsiveswitch-controlling means; means associated with said counting mechanismfor causing the opening of said control-valve at the end of apredetermined count of rapidly recurrent line-fault responses; and meansresponsive to an opening movement of said drive-mechanism fordiscontinuing the operation of the blastvalve.

4. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufiicient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mountedcompressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallyclosed blast-valve for controlling the communication between saidblast-tube and the tank, an electrically controlled fault-responsivemeans for causing the operation of the blast-valve during line-faultconditions on the circuit-breaker and for interrupting the operation ofthe blast-valve during fault-free conditions; a counting mechanism forcounting rapidly recurrent line-fault responses and for operating, atthe end of a predetermined count, to cause the operation of theblast-valve to continue independently of fault conditions; anisolating-switch; means for electrically connecting the isolating-switchin series-circuit relation to the interrupter-assembly; a drivemechanism foropening and closing the isolating switch; a pressureresponsive s vitch-controlling means for automatically controlling theactuation of said drive-mechanism in the switch-opening direction inresponse to the air-pressure in the blast-tube of the interrupterassembly; and means responsive to an opening movement of saiddrive-mechanism for discontinuing the operation of the blast-valve.

5. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufficient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mountedcompressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallyclosed blast-valve for controlling the communication between saidblast-tube and the tank, an electrically controlled fault-responsivemeans for causing the operation of the blast-valve during line-faultconditions on the circuit-breaker and for interrupting the operation ofthe blast-valve during fault-free conditions; a counting mechanism forcounting rapidly recurrent line-fault responses and for operating, atthe end of a predetermined count, to cause the operation of theblastvalve to continue independently of fault-conditions; anisolating-switch; means for electrically connecting the isolating-switchin series-circuit relation to the interrupter-assembly; adrive-mechanism for opening and closing the isolating switch; a pressureresponsive switch-controlling means for automatically controlling theactuation of said drive-mechanism in the switch-opening direction 'inresponse to the air-pressure in the blast-tube of theinterrupterassembly; a normally closed switch-opening control valve insaid pressure responsive switchcontrolling means; means associated withsaid counting mechanism for causing the opening of said control-valve atthe end of a predetermined count of rapidly recurrent line-faultresponses; and means responsive to an opening movement of saiddrive-mechanism for discontinuing the operation of the blast-valve.

6. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a suflicient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, a compressed-air tank alsosupported by said insulating supporting means at an elevated potential,a short blast-tube for at times supplying said interruptergap devicewith an air-blast ,from said tank, and a normally closed blast-valve forcontrolling the communication between said blast-tube and the tank, at

least one of the contacts of said main inter rupter-gap device beinghollow and having an orifice at its front end and having a substantiallyclosed exhaust-chamber at its rear end, the abutment of said contacts inthe normal closed position of the interrupter-gap, device substantiallycovering said orifice; in combination with: a dump-valve which isoperable at times to quickly dump the compressed air out of saidexhaust-chamber; means for actuating the blastvalve; and means forautomatically actuating the dump-valveafter the substantial completionof the interrupting operation of the interrupterassembly. 1

'7. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supportingsaidinterrupter-assembly at a sufficient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, a compressed-air tank alsosupported by said insulating supporting means at an elevated potential,a short blast-tube for at times supplying said interrupter gap devicewith an air-blast from said tank, and a normally closed blast-valve forcontrolling the communication between said blast-tube and the tank, atleast one of the contacts of said main interrupter-gap device beinghollow and having an orifice at its front end and having a substantiallyclosed exhaust-chamber at its rear end, the abutment of said contacts inthe normal closed position of the interrupter-gap device substantiallycovering said orifice; in combination with: a dump-valve which isoperable at times to quickly dump the compressed air out of saidexhaust-chamber; an electrically controlled fault-responsive means forcausing the operation of the blast-valve during line-fault conditions onthe circuit-breaker; means for automatically actuating the dump-valveafter the substantial completion of each interrupting operation of theinterrupter-assembly; an isolating-switch; means for electricallyconnecting the isolating-switch in series-circuit relation to theinterrupter assembly; a drive mechanism for opening and closing theisolating-switch; and a pressure-responsive switch-controlling means forautomatically controlling the actuation of said drive-mechanism in theswitchwpening direction in response to the air-pressure in the blasttubeof the interrupter-assembly.

8. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufficient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally of the interrupter-gap devicessubstantially covering said orifice; in combination with: a dump-valvewhich is operable at times to quickly dump the compressed air out ofsaid exhaustchamber; an electrically controlled fault-responsive meansfor causing the operation of the blast-valve during linefault conditionson the circuit-breaker and for interrupting the operation of theblast-valve during fault-free conditions; a counting mechanism forcounting rapidly recurrent line-fault responses and for operating, atthe end of a predetermined count, to cause the operation of theblast-valve to continue independently of fault-conditions; means forautomatically actuating the dump-valve after the substantial completionof each interrupting operation of the interrupter-assembly; an isolating-switch; means for electrically connecting the isolating-switch inseries-circuit relation to the interrupter-assembly; a drive-mechanismfor opening and closing the isolating-switch; a pressure-responsiveswitch-controlling means for antomatically controlling the actuation ofsaid drive-mechanism in the switch-opening direction; a normally closedswitch-opening contro valve in said pressure-responsiveswitchcontrolling means; means associated with said counting mechanismfor causing the opening of said control-valve at the end of apredetermined count of rapidly recurrent line-fault responses; and meansresponsive to an opening movement of said drive-mechanism fordiscontinuing the operation of the blast-valve.

9. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufhcient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mountedcompressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallyclosed blast-valve for controlling the communication between saidblast-tube and the tank, at least one of the contacts of said maininterrupter-gap device being hollow and having an orifice at its frontend and having a substantially closed exhaust-chamber at its rear end,the abutment of said contacts in the normal closed position of theinterrupter-gap device substantially covering said orifice; incombination with: a dumpvalve which is operable at times to quickly dumpthe compressed air out of said exhaust-chamber; an electricallycontrolled fault-responsive means for causing the operation of theblast-valve during line-fault conditions on the circuit-breaker trollingthe actuation of said drive-mechanism in the switch-opening direction inresponse to the air-pressure in the blast-tube of the interrupterassembly; and means responsive to an opening movement of saiddrive-mechanism for discontinuing the operation of the blast-valve.

10. A compressed-air circuit-breaker assembly comprising: an air-blastinterrupter-assembly; insulating supporting-means for supporting saidinterrupter-assembly at a sufficient insulatingdistance from asubstantially ground-potential surface to withstand a substantialelevated linepotential; said interrupter-assembly comprising a maininterrupter-gap device having normally closed contacts which areseparable in response to an air-blast, an adjacently mountedcompressed-air tank, a short blast-tube for at times supplying saidinterrupter-gap device with an air-blast from said tank, and a normallyclosed blast-valve for controlling the communication between saidblast-tube and the tank, at least one of the contacts of said maininterrupter-gap device being hollow and having an orifice at its frontend and having a substantially closed exhaust-chamber at its rear end,the abutment of said contacts in the normal closed position of theinterrupter gap device substantially covering said orifice; incombination with: a dump-valve which is operable at times to quicklydump the compressed air out of said exhaust-chamber; an electricallycontrolled fault-responsive means for causing the operation of theblast-valve during line-fault conditions on the circuit-breaker and forinterrupting the operation of the blast-valve during fault-freeconditions; a counting mechanism for counting rapidly recurrentline-fault responses and for operating, at the end of a predeterminedcount, to cause the operation of the blast-valve to continueindependently of faultconditions; means for automatically actuating thedump-valve after the substantial completion of each interruptingoperation of the interrupterassembly; an isolating-switch; means forelectrically connecting the isolating-switch in series-circuit relationto the interrupter-assembly; a drive-mechanism for opening and closingthe isolating switch; a pressure-responsive switchcontrolling means forautomatically controlling the actuation of said drive-mechanism in theswitch-opening direction in response to the airpressure in theblast-tube of the interrupter-assembly; a normally closed switch-openingcontrol valve in said pressure responsive switchcontrolling means; meansassociated with said counting mechanism for causing the opening of saidcontrol-valve at the end of a predetermined count of rapidly recurrentline-fault responses; and means responsive to an opening movement ofsaid drive-mechanism for discontinuing the operation of the blast-valve.

11. A compressed-air circuit-breaker assembly comprising: acompressed-air source; an airblast interrupter-assembly, saidinterrupter-assembly comprising a hollow elongated stationarycontact-member having an orifice in its front end, a substantiallyclosed exhaust-chamber at the rear end of said stationary contact-memberin air-communication with its hollow interior, and a moving-contactassembly comprising a spring-closed, longitudinally movablecontactmember normally abutting against the front end of said stationarycontact-member and in such position substantially covering said orifice;a blast-tube for at times supplying said interrupterassembly with anair-blast from said compressedair source; a normally closed blast-valvefor controlling the communication between said blast-tube and. said.compressed-air source; a pressure-responsive dump-valve for at timesquickly dumping the compressed air out ofv said exhaust chamber, saiddump-valve being openable in responseto air-pressure within said eX-haust-charnber. and being closable in response to an externally appliedair -pressure; a pilot dump-valve operable, in its non-actuatedposition, to vent said dump-valve so that it has no externally appliedair-pressure, said pilot dumpvalve being operable, in its actuatedposition, to furnish said dump-valve with externally appliedair-pressure from the blast-tube of the inter rupter-assembly; and meansfor actuating both the blast-valve and the pilot dump-valve.

' 12. A reclosing compressed-air circuit-breaker assembly comprising: acompressed-air source; an air-blast interrupter-assembly, saidinterrupter-asseinbly comprising normally closed contacts which areseparable in response to an air-blast; a blast-tube for at timessupplying said interrupterassembly with an air blast from saidcompressedair source; a normally closed blast'valve for controlling thecommunication between said blasttube and said compressed-air source; anelectrically controlled fault-responsive means for causing the operationof the blast-valve during line-fault conditions on the circuit-breakerand for interrupting the operation of the blast-valve during fault-freeconditions; a counting mechanism for counting rapidly recurrentline-fault responses and for operating, at the end of a predeterminedcount, to cause the operation of the blast valve to continueindependently of faultconditions; an isolating-switch; means forelectrically connecting the isolating-switch in seriescircuit relationto the interrupterassembly; a drive-mechanism for opening and closingthe isolating switch; a pressure-responsive switch-com trolling meansfor automatically controlling the actuation of said drive-mechanism inthe switchopening direction; a normally closed switchopeningcontrol-valve in said pressure-responsive switch-controlling means;means associated with said counting mechanism for causing the opening ofsaid control-valve at the end of a predetermined count of rapidlyrecurrent line-fault responses; and means responsive to an openingmovements)? said drive-rnechanism for discon tlnuing the operation ofthe blast-valve.

13. A reclosing compressed-air circuit-breaker assembly comprising: acompressed-air source; an air-blast interrupter-assembly, saidinterrupter-assembly comprising normally closed contacts which areseparable in response to an air-blast; a blast-tube for at timessupplying said interruptei assembly with an air-blast from saidcompressed-air source; a normally closed blast-valve for controllingthecommunication between said blast-tube and said compressed-air source; an

electrically controlled faultresponsive means for causing the operationof the blast-valve during line-fault conditions on the circuit'breakerand for interrupting the operation of the blast-valve during fault-freeconditions; a counting mechanism for counting rapidly recurrentline-fault responses and for operating, at the end of a predeterminedcount, to cause the operation of the blast-valve to continueindependently of faultconditions; an isolating-switch; means forelectrically connecting the isolating-switch in seriescircuit relationto the interrupter-assembly; a drive-mechanism for opening and closingthe 18 isolating-switch; a pressure-responsive switchcontrolling meansfor automatically controlling the actuation of said drive-mechanism inthe switch-opening direction in response to the air pressure in theblast-tube of the interrupterassembly; and means responsive to anopening movement of said drive-mechanism for discontinuing the operationof the blast-valve 14. A reclosing compressed-air circuitbreakerassembly comprising: a compressed-air source; an airblast interrupterassembly, said interrupter-assembly comprising normally closed contactswhich are separable in response to an airblast; a blast-tube for attimes supplying said interrupter-assembly with an air-blast from saidcompressed-air source; a normally closed blastvalve for controlling thecommunication between said blast-tube and said compressed-air source; anelectrically controlled fault-responsive means for causing the operationof the blast-valve during line-fault conditions on the circuit-breakerand for interrupting the operation of the blastvalve duringfault-freeconditions; a counting mechanism for counting rapidly recurrentlinefaultresponses and for operating, at the end of a predetermined count, tocause the operation of the blast-valve to continue independently offault-conditions; an isolating-switch; means for electrically connectingthe isolatin -switch in series-circuit relation to the interrupter-assenbly; a drive-mechanism for opening and closing the isolating-switch; apressure-responsive switch-controlling means for automaticallycontrolling the actuation of said drive-mechanism in the switch-openingdirection in response to the air-pressure in the blast-tube of theinterrupter-assembly; a normally closed switch-opening control-valve insaid pressure-responsive switch-controlling means; means associated withsaid counting mechanism for causing the opening of said control-valve atthe end of a predeter mined count of rapidly recurrent line-faultresponses; and means responsive to an opening movement of saiddrive-mechanism for discontinuing the operation of the blast-valve.

15. A compressed-air circuit-breaker assembly comprising: acompressed-air source; an air-blast interrupter-assembly, saidinterrupter-assembly comprising a hollow elongated stationarycontact-member having an orifice in its front end, a substantiallyclosed exhaust-chamber at the rear end of said stationary contact-memberin air-communication with its hollow interior, and a moving-contactassembly comprising a spring closed, longitudinally movablecontact-member normally abutting against the front end of saidstationary contactmember and in such position substantially coveringsaid orifice; a blast-tube for at times supplying saidinterrupter-assembly with an air-blast from said compressed-air source;a normally closed blast-valve for controlling the communication betweensaid blast-tube and saidcompressed-air source; a dump-valve which isoperable at times to quickly dump the compressed air out of saidexhaustchamber; means for actuating the blast-valve; and means forautomatically actuating the dump-valve after the substantial completionof the interrupting op-- eration of the interrupter assembly.

16. A compressed-air circuit-breaker assembly comprising: acompressed-air source; an airblast interrupter-assembly, saidinterrupter-assembly comprising normally closed contacts which areseparable in response to an air blast, at least one of said contactsbeing hollow andhaving an orifice atits front end and having asubstantially closed exhaust-chamber at its rear end; the abutment ofsaid contacts in the normal closed position of the interrupter-assemblysubstantially covering said orifice; a blast-tube for at times supplyingsaid interrupter-assembly with an air-blast from said compressed-airsource; a normally closed blast-valve for controlling the communicationbetween said blast-tube and said compressed-air source; a dump-valvewhich is operable at times to quickly dump the compressed air out ofsaid exhaust-chamber; means for actuating the blast-valve; and means forautomatically actuating the dump-valve after the substantial completionof the interrupting operation of the interrupter-assembly.

1'7. A reclosing compressed-air circuit-breaker assembly comprising; acompressed-air source; an air-blast interrupter-assembly, saidinterrupter-assembly comprising normally closedicontacts which are separable inresponse to an air-blast, at least one of said contacts being hollow andhaving an orifice at its front end and having a substantially closedexhaust-chamber at its rear end, the abutment of said contacts in thenormal closed position of the interrupter-assembly sub stantiallycovering said orifice; a blast-tube for at times supplying saidinterrupter-assemblywith an air-blast from said compressed-air source; anormally closed blast-valve for controlling the communication betweensaid blast-tube and said compressed-air source; a dump-valve which isoperable at times to quickly dump the compressed air out of saidexhaust-chamber; an electrically controlled fault-responsive means forcausing the operation of the blast-valve during line-fault conditions onthe circuit-breaker; means for automatically actuating the dump-valveafter the substantial completion of each interrupting operation of theinterrupter-assembly; an isolatingswitch; means for electricallyconnecting the isolating-switch in series-circuit relation to theinterrupter-assembly; a drive-mechanism for opening and closing theisolating-switch; and a pressure-responsive switch-controlling means forautomatically controlling the actuation of said drive-mechanism in theswitch opening direction in response to the air-pressure in theblast-tube of the interrupter-assembly.

18. A reclosing compressed-air circuit-breaker assembly comprising: acompressed-air source; an air-blast interrupter-assembly, saidinterrupter-assembly comprising normally closed contacts which areseparable in response to an air-blast, at least one of said contactsbeing hollow and having an orifice at its front end and having asubstantially closed exhaust-chamber at its rear end, the abutment ofsaid contacts in the normal closed position of the interrupter-assemblysubstantially covering said orifice; a blast-tube for at times supplyingsaid interruptei assembly with. an air-blast from said compressed-airsource; a normally closed blast-valve for controlling the communicationbetween said blasttube and said compressed-air source; a dump-valvewhich is operable at times to quickly dump the compressed air out ofsaid exhaust-chamber; an electrically controlled fault-responsive meansfor causing the operation of the blast-valve during line-faultconditions on the circuit-breaker and for interrupting the operation ofthe blast-valve during fault-free conditions; a counting mechanism forcounting rapidly recurrent line-fault responses and for operating, atthe end of a predetermined count, to cause the operation of theblast-valve to continue: independently of. fault-conditions; means forautomatically actuating the dumpvalve after substantial completion ofeach interrupting operation of the interrupter-assembly; anisolating-switch; means for electrically connecting the isolating-switchin series-circuit relation to the interrupter-assembly; adrive-mechanism for opening and closing the isolatingswitch; apressure-responsive switch-controlling means for automaticallycontrollin the actuatlon of said drive-mechanism in the switch-openingdirection; a normally closed switch-opening control-valve in saidpressure-responsive switchcontrolling means; means associated with saidcounting mechanism. for causing the opening of said control-valve at.the end of a predetermined count of rapidly recurrent line-faultresponses; and means responsive to an opening movement of saiddrive-mechanismfor. discontinuing the operation of the blast-valve.

19. A reclosing compressed-air circuit-breaker assembly comprising: acompressed-air source; an air-blast interrupter-assembly, saidinterrupter assembly comprising normally closed contacts which areseparable in response to an airblast, at least one of said contactsbeing hollow and having an orifice at its front end and having asubstantially closed exhaust-chamber at its rear end, the abutment ofsaid contacts in the normal closed position of the interrupter-assemblysubstantially covering said orifice; a blasttube for at times supplyingsaid interrupter-assembly with an air-blast from said compressedairsource; a normally closed blast-valve for corn trolling thecommunication between said blasttube and said compressed-air source; adumpvalve which is operable at times to quickly dump the compressed airout of said exhaust-chamber; an electrically controlled fault-responsivemeans for causing the operation of the blast-valve during line-faultconditions on the circuit-breaker and for interrupting the operation ofthe blastvalve during fault-free conditions; a counting mechanism forcounting rapidly recurrent linefault responses and for operating, at theend of a predetermined count, to cause the operation of the blast-valveto continue independently of fault-conditions; means for automaticallyactuating the dump-valve after substantial completion of eachinterrupting operation of the interrupter-assembly; an isolating-switch;means for electrically connecting the isolating-switch in series-circuitrelation to the interrupter assembly; a drive-mechanism for opening andclosing the isolating-switch; a pressure-responsive switch controllingmeans for automatically controlling the actuation of saiddrive-mechanism in the switch-opening direction in response to theair-pressure in the blast-tube of the interrupter-assembly; and meansresponsive to an opening movement of said drive-mechanism fordiscontinuing the operation of the blast-valve.

20. A reclosing compressed-air circuit-breaker assembly comprising: acompressed-air source; and air-blast interrupter-assembly, saidinterrupter-assembly comprising normally closed contacts which areseparable in response to an air blast, at least one of said contactsbeing hollow and having an orifice at its front end and having asubstantially closed exhaust-chamber at its rear end, the abutment ofsaid contacts in the normal closed position of the interrupterassem blysubstantially covering said orifice; a blasttube for at times supplyingsaid interrupter-assembly with an air-blast from said compressedairsource; a normally closed blast-valve for controlling the communicationbetween said blasttube and said compressed-air source; a dumpvalve whichis operable at times to quickly dump the compressed air out of saidexhaust-chamber; an electrically controlled fault-responsive means forcausing the operation of the blast-valve during line-fault conditions onthe circuit-breaker and for interrupting the operation of the blastvalveduring fault-free conditions; a counting mechanism for counting rapidlyrecurrent line-= fault responses and for operating, at the end of apredetermined count, to cause the operation of the blast-valve tocontinue independently of fault-conditions; means for automaticallyactuating the dump-valve after substantial completion of eachinterruptin operation of the interrupter-assembly; an isolating-switch;means for electrically connecting the isolating-switch in series-circuitrelation to the interrupter-assembly; a drive-mechanism for opening andclosing the isolating-switch; a pressure-responsive switch-controllingmeans for automatically controlling the actuation of saiddrive-mechanism in the switch-opening direction in response to 2 22 theair-pressure in the blast-tube of the interrupter-assembly; a normallyclosed switch-opening control-valve in said pressure-responsiveswitch-controlling means; means associated with said counting mechanismfor causing the opening of said control-valve at the end of apredetermined count of rapidly recurrent line-fault responses; and meansresponsive to an opening movement of said drive-mechanism fordiscontinuing the operation of the blast-valve.

BENJAMIN P. BAKER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,175,902 Korndorfer Oct. 10, 1939 2,287,039 Jansson June 23,1942 2,364,981 Journeaux Dec. 12, 1944 2,392,647 Cox Jan. 8, 1946FOREIGN PATENTS Number Country Date 511,757 Great Britain Aug. 23, 1939522,514 Great Britain June 20, 1940

